Tuesday 8 October 2013

What Are the Differences Between the Major Robotic Lawn Mower Brands

Most robotic lawnmowers operate on the same basic principles with the same key features:

  • mulching blades (small amount of grass cut, drops onto the lawn)
  • powerful wheels (to deal with slopes)
  • sensors (to avoid obstacles)
  • guide wire (to keep within one or more zones)

However, within these principles there is scope for quite a lot of variation, and some of the variations serve to differentiate the models on offer.

Of course, as always, one of the biggest differentiating factors is price. Across the ranges, prices can triple, so it's worth knowing what you are (potentially) getting for your money.

Different Blades

Underneath any lawn mower, be it a Flymo hovering mower, or a Briggs and Stratton powered petrol guzzling traditional push around mower, there are one or more blades.

Traditional mowers are built to cut through long grass that has either been neglected over the off-season, or needs cutting every week (and only gets cut once a week) with the clippings being taken off to be disposed of.

Robotic mowers are designed for one purpose - to cut automatically and regularly, and drop the grass tips down onto the lawn to mulch it; automatically providing nutrition as well as keeping the lawn trim.


Most of the mowers on the market have multiple blades, held in place by a screw, which spin around at great speed, clipping the tips of the grass, and then chopping those tips into a fine dust.

Above right, are the blades for a Bosch Indego mower, which are long and thin.

To the left are the blades from a Gardena / Husqvarna, and Flymo mower, all of which seem to be either manufactured by Husqvarna in different liveries, or made under license.

Then, there are the single blade varieties, such as those used by RoboMow models, as pictured on the right.

So, which is the best?

Naturally, each manufacturer will have their reasons, but from the point of view of the mulching process, I have an idea that the loose blades might provide a better cutting action.

However, they are also more likely to snap (it's happened twice on my Gardena/Husqvarna) and fall off. I have a sneaking suspicion that the single piece blades are less likely to fail, but more likely to do damage should they come off.

Different Wheels

There are really only two choices for wheel arrangements - thee or four wheels - but again there is a surprising amount of variety across brands. Originally, Husqvarna went with a three wheel model, with the rear single wheel being smaller, and on a pivot.

This is very similar to the Flymo wheel arrangement, pictured on the left.

It has been replaced in more recent models with a version that has the smaller wheel at the front, like the Bosch Indego, and which, like the Bosch also enters the charging station front-first as opposed to back-first like the smaller Flymo models

Different Control Styles

All mowers need to have sensors to avoid hitting obstacles (like dogs, cats or trees!) and these are usually in the form of bumpers. Bumpers are reliable in a way that, for example, an ultrasound sensor might not be.

Next to the bumpers are different remote control styles - some mowers have a control pad that lets the owner steer the mower from zone to zone, while most just take themselves to a new zone by following a guide wire.

The guide wire is accompanied by a perimeter wire, which restricts the mower to the current zone. Many manufacturers also sell a kit to add new zones, so that the mower can be used on a greater area than originally installed.

Finally, some more recent models are starting to use GPS (Global Positioning System) antennas to help map out the space that needs to be mowed, and also to make sure that the whole area has been cut.

This last is important because, like some robotic vacuum cleaners, most of the models on the market tend to mow in a random fashion, over an extended period of time, and use this to make sure that the whole lawn has been cut.

Some of the more expensive models also have other cutting modes, so that they can be adapted to different shapes of lawn. So, if you have a lawn that is (a) large and (b) has many obstacles as well as (c) being an odd shape, it's probably worth spending a bit extra to get a more clever mower.

One last differentiating factor is the charging station. While most manufacturers have spotted that this needs to be weatherproof and located outside, some of the cheaper models still have an indoor charging station and require the mower to be carried or driven from the garage to the lawn.

Clearly, in the interests of automatic mowing, and ease of use, an outdoor charging station is the way to go.

Armed with this rundown of the various different features of automatic robotic lawn mowers, you should now be ready to choose from the models on the market, and join the rest of us who can sit back and watch whilst our lawns are carefully and immaculately mowed!

3 comments:

  1. Nice to see this blog - the Net is very short on info on these things. I bought a Honda Miimo last year, and now I really regretting it. I dont't think it's the fault of the Honda - I think any robomower would struggle with my lawn. First and foremost, there are foxes around that seem to delight in biting through the perimeter wire, just out of badness. And as you point out in your blog finding a break means shuffling round the garden on all fours tugging at the wire - then there's the challenge of mending it so it's watertight and safe. And then you have to hope there isn't another break somewhere else...

    Add to that the problem of kids leaving stuff lying in the garden that either get damaged by the mower or damage the mower, or obstacles that it's supposed to be able to navigate but can't (ie goalposts) plus a propensity for getting stuck behind unfortunately placed trees... it would have been much much simpler in the end to get a traditional mower and do the bloody job myself.

    Apart from anything else, I'm planning to redesign the garden - which will mean pulling up and relaying the perimeter wire. With a traditional mower you can do what you like to your garden without worrying about any of that crap.

    Bottom line: Unless you have a lawn like a tennis court that kids never use, robomowers are not worth the faff or the expense. Strictly for gadget freaks with more money than sense.

    Sorry to be negative on your blog, but I had to vent somewhere!

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    Replies
    1. Hello, and thanks for taking the opportunity to vent!

      For the benefit of the audience, let's look at these one at a time.

      Problem #1 : Nasty Little Rodents (& Foxes)

      These can make a real mess of your perimeter wire, as pointed out by the commenter. There are a number of solutions - starting with the most obvious: buy a mower with GPS!

      They're both pricey and not terribly accurate, so let's look at some other options. You can always bury the cable - that will help (except for moles) - but then you'll have to rip it up every time you remodel the garden!

      My preferred alternative is to place the wire very near the surface but protect it using an outer tube. Most (if not all) systems can cope with this (after all, you would otherwise be burying the wire!)

      Fixing broken wires is, predictably, a pain. And there's not a whole lot anyone can do about that. Personally, I have a long piece of wire (30m) that I keep specifically for troubleshooting broken connections.

      At one end it has a customized crocodile clip that is capable of making a connection through the wire but not cutting it. This helps me to find breaks, but to do so, I need to cut through the protecting tube, of course.

      Making the (repaired) connections watertight is easy enough - 3M sell a little widget for that; it's a 3-way connector with a waterproofing system that's activated by squeezing it with a pair of pliers.

      Issue #2 : Obstacles (& Children!)

      yes, children leaving things on the lawn is an issue. As is hanging washing on the line, it falling off, and the mower chewing it up. To be fair, I also managed to do that myself with the 'manual' mower, but still...

      I'll agree, too, that sometimes the garden can have non-moveable objects such as trees that make a mess of the navigation. If you have a garden that is an odd shape, I would buy a mower that has more than one single mode; or one that has a variable mode.

      That way, it'll likely get itself 'unstuck' or just not get stuck in the first place. However, not every lawn is 100% robot mower friendly, but most can be adapted.

      #3 : Remodelling (the garden)

      I'll be a bit snide and crass here, but there's a serious point behind it: if you're going to redesign the lawn, why not redesign it to be mower-friendly ;)

      Seriously, though, I do understand, but I'm not someone who will ever remodel their own lawn because I don't care enough about how it looks. I just want the grass short, and as few flowers as possible, and the design of the garden follows that ethos.

      So, it could be the perfect lawn for a robotic mower (kids aside!), but it isn't for everyone.

      And that's the real bottom line - and what I thought you were trying to get at with the slightly negative ending - if you have a reasonably unchallenging lawn, hate mowing, and want it to be a rich, deep green, mole-free, then a robotic lawnmower is for you!

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  2. Thanks for sharing this very informative post.

    ReplyDelete